A number of processes for producing a lining on the inner walls of a metallurgical vessel are known. Thus, for example, there is known, according to French Patent 2,393,637, a process in which an aqueous and pasty mixture capable of setting, containing inorganic particles, optionally fibers, and an organic and/or inorganic binder, is applied by molding, tamping or projecting with the trowel or pneumatic or other projecting to the inside of a metallurgical vessel such as a casting tundish. The mixture of particles sinters in contact with the liquid metal, and this ensures the cohesion of the lining.
According to French Patents 2,585,273, 2,613,256 and 2,619,323 there is also known a process according to which at least two layers of different compositions are applied to the inside of the metallurgical vessel, each being applied by projecting an aqueous and pasty mixture capable of setting of the above-mentioned type.
These processes, which otherwise give the users complete satisfaction, nevertheless present a disadvantage: at least all the wetting water employed for forming the aqueous mixture(s) must be removed by drying, and this involves an immobilization time and an expenditure of energy, neither of which can be ignored.
There is also known a process according to which a template is placed inside a metallurgical vessel, a material consisting of refractory particles and of a heat-curable binder is projected pneumatically between the template and the inner walls of the vessel, and heating is then applied while the template is left in place to cause the binder to set, and the template is finally removed. The cast material contains an inorganic compound containing water of crystallization.
It is also known that refractory bodies can be made by casting of refractory concretes either by vibration casting of a wet concrete or by vibration-free casting the concrete having a self-flowing consistency. In both approaches, all concrete materials need to be homogeneously mixed and wetted.
Mixing of concrete in a homogeneous way which has very fine and coarse particles is difficult to achieve and needs high energy mixing equipment. In case of vibration casting, the used molds have to be strong enough to withstand vibration. When casting more complicated linings, i.e., steel ladles, the casting has to be done in separate steps. The bottom of the ladle can be cast; and before the mold for the wall can be introduced, the castable has to reach sufficient mechanical strength.
Producing castables of highly porous materials by conventional vibration of vibration-free casting requires large quantities of mixing water (in excess of 15%) due to the fact that the mixing water fills up the open pores of the material. A high mixing water content in the castable means very long dry-out times and poor mechanical strength.
In order to increase thermal shock resistance, fibrous materials have been used in vibration and self-flowing materials. The use of fibrous materials increases the need for high levels of mixing water and makes casting more difficult. Very coarse materials which are beneficial for slag resistance due to their high density can only be used to a certain extent, because casting of concretes with a very high content of coarse materials is very difficult.
The aim of the present invention is to overcome the disadvantages of the known processes and to propose a process which is simple, rapid and economical to employ and which is particularly well suited to the production of a lining of a metallurgical or glass vessel.
These and other objects and advantages of the present invention will be more fully understood and appreciated with reference to the following description.